Plants with plum-coloured leaves may need more pampering but they’re worth it, says Monty Don

My purple patch! Plants with plum-coloured leaves may need more pampering but they’re worth it for the splash of colour they serve up, says Monty Don

  • Monty Don says purple-leaved plants need more pampering than green-leaved
  • British gardening expert claims purple-leaved plants add more depth to a border
  • He reveals purple-leaved plants in his Jewel Garden need light to thrive

Monty revisits one of his classic books, Gardening at Longmeadow, in an occasional series. 

Purple leaves, which are coming into their full glory now, will make red and yellow flowers seem more intense, and add more depth to a border than any green can, so they are particularly suitable for the Jewel Garden. 

I was first struck by how effective purple foliage can be in the garden of Kiftsgate Court near Chipping Campden in Gloucestershire. The way that purple hazels were coppiced there influenced me dramatically. 

Monty Don shared his advice for adding depth to borders with purple-leaved plants, as he reveals they need more pampering than green-leaved ones. Pictured: An arch of Corylus maxima ‘Purpurea’

Coppicing the shrubs – in other words regularly cutting them right to the ground – produces vigorous new shoots that carry extra-large leaves. 

After that visit to Kiftsgate I bought some purple hazels, Corylus maxima ‘Purpurea’, and sat back to watch them become healthy plants.

Our coppice is made up of 73 green hazels, Corylus avellana, which all grow lustily, so I assumed their purple cousins would perform just as well in the Jewel Garden. No such luck. 

YOUR KITCHEN GARDEN: ASPARAGUS

You can easily buy fresh asparagus, but it is nothing like as good as spears from your garden. Like sweetcorn, new potatoes or peas, this is a harvest that diminishes in quality almost by the minute.

Monty said asparagus is best planted 30cm apart with 15cm of soil above

Monty said asparagus is best planted 30cm apart with 15cm of soil above

You can grow it from seed, but it is more usual to buy crowns or one-year-old plants. They’re best planted 30cm apart with 15cm of soil above. Spread the roots very carefully as they are brittle, but never let them dry out. 

I left a batch in the sun for just half an hour once and not one grew. If you start with crowns planted when the soil has warmed up you’ll take your first harvest the following year, a more substantial one the next, and tuck in with relish in year three. 

Each plant can give 30-40 spears over the season. In humid weather the spears can grow several centimetres a day, but in a cool week there can be very little growth – a layer of fleece or cloches can help.

It grows well on any fertile ground but drainage is key, so grow on a ridge or add lots of grit and plant 15-23cm deep. Male plants are often healthier – try ‘Lucullus’, ‘Grolim’, ‘Purple Passion’, ‘Backlim’ and ‘Gijnlim’.

Stop cutting in July and let the shoots develop foliage, then cut back in autumn and mulch in early spring.

For years they hardly grew at all, so I eventually replanted them in a nursery bed, where, to my surprise, they flourished – not only producing purple leaves but also pink- and magenta-tinged nuts. Finally I worked out what the problem was.

Although planted in an open border, they were nevertheless being shaded out by the vigour of the annuals that I grow in those beds, particularly Atriplex hortensis var. rubra, the purple orach, which is a prodigious self-seeder. 

It took me a while to realise that an annual with a life of just a few months could crush the will to live in a small tree. In the end I bought four more much larger purple hazels and planted them in exactly the same spot and they thrived – because their foliage was never competing for precious light.

However, I don’t coppice right to the ground because the young shoots would face the same problem as the first batch of plants, so I selectively prune a third down to the ground every winter, leaving enough up in the light to nourish the roots. It works well.

If they had green leaves they would probably have coped with the lack of light but the red layer of pigment over the green of the chlorophyll means less photosynthesis and therefore less nourishment. In short, purple-leaved plants need more pampering than green-leaved ones and, if they are to grow at all strongly, more light.

As well as the hazels in the Jewel Garden borders we also have a few other purple-leaved shrubs to act as a backdrop to increase the intensity of colour, especially in late summer. 

There is the smoke bush, Cotinus coggygria ‘Royal Purple’, which has excellent burgundy leaves with a touch of brown. C. c. ‘Velvet Cloak’ is good too. I also have a purple elder, Sambucus nigra f. porphyrophylla ‘Guincho Purple’. 

This is so vigorous it will take a really hard prune every year, outgrowing the competition for light around it, but the cotinus need plenty of light.

You do not have to use shrubs for your foliage plants. I also grow Lysimachia ciliata ‘Firecracker’, a perennial with chocolate leaves and little yellow flowers. It is superb if you have dampish soil, although it flops badly in dry conditions. 

If happy, it spreads like wildfire and needs reducing by as much as three-quarters every few years to keep it under control. 

HOW TO USE YOUR NETTLES 

  • Despite being a major weed in my garden, I would not be without nettles (right). Even though they grow where not wanted and occasionally sting appallingly, they are easy to dig up and are also a huge improvement to the compost heap.
  • Every garden should have a patch of nettles, as they are a major source of food for butterflies, such as the red admiral. They are good food for humans, too. Spring nettles are rich in iron: pick the fresh tips of each stem and cook them like spinach. Cooking destroys any risk of stinging.
  • Soak 500g of nettles in a 5-litre bucket of water for two weeks. Use as a liquid feed – and a general plant boost – diluting the nettle liquid with 10 parts water, once a week at most. Remember over-feeding, especially young plants, does more harm than good.

Extracted from Gardening At Longmeadow by Monty Don, BBC Books, £26. © Monty Don 2012